[String-easy] 709. To Lower Case given string uppercase to lowercase letters are

1. The title site

https://leetcode.com/problems/to-lower-case/

2. Title Description

3. subject to the effect

Sign problem

The given string uppercase letters to lowercase letters

4. Problem-solving ideas

Variable use StringBuilder type of increase in character, whether it is in accordance with the lowercase letters into StringBuilder type variable species, add character if not a lowercase letter becomes a lowercase letter.

5. AC Code

class Solution {
    public String toLowerCase(String str) {
        StringBuilder sb = new StringBuilder();
        for(int i = 0; i < str.length(); i++) {
            char temp = str.charAt(i);
            if(temp >= 'a' && temp <= 'z') {
                sb.append(temp);
            } else if(temp >= 'A' && temp <= 'Z'){
                sb.append((char)(temp - 'A' + 'a'));
            } else {
                sb.append(temp);
            }
        }
        return new String(sb);
    }
}